Germ-line regulation of the Caenorhabditis elegans sex-determining gene tra-2

Dev Biol. 1998 Dec 1;204(1):251-62. doi: 10.1006/dbio.1998.9062.


The Caenorhabditis elegans sex-determining gene tra-2 promotes female development of the XX hermaphrodite soma and germ line. We previously showed that a 4.7-kb tra-2 mRNA, which encodes the membrane protein TRA-2A, provides the primary feminizing activity of the tra-2 locus. This paper focuses on the germ-line activity and regulation of tra-2. First, we characterize a 1.8-kb tra-2 mRNA, which is hermaphrodite-specific and germ-line-dependent. This mRNA encodes TRA-2B, a protein identical to a predicted intracellular domain of TRA-2A. We show that the 1.8-kb mRNA is oocyte-specific, suggesting that it is involved in germ-line or embryonic sex determination. Second, we identify a tra-2 maternal effect on brood size that may be associated with the 1.8-kb mRNA. Third, we investigate seven dominant tra-2(mx) (for mixed character) mutations that sexually transform hermaphrodites to females by eliminating hermaphrodite spermatogenesis. Each of the tra-2(mx) mutants possesses a nonconserved missense change in a 22-amino-acid region common to both TRA-2A and TRA-2B, called the MX region. We propose that the MX region mediates a posttranslational regulation of tra-2 essential for the onset of hermaphrodite spermatogenesis. Finally, we discuss aspects of tra-2 function and regulation that are specific to the unusual control of cell fate in the hermaphrodite germ line.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Caenorhabditis elegans / embryology
  • Caenorhabditis elegans / genetics*
  • Drosophila Proteins*
  • Female
  • Gene Expression Regulation, Developmental*
  • Male
  • Molecular Sequence Data
  • Oogenesis / genetics
  • Ribonucleoproteins / genetics*
  • Sequence Alignment
  • Sex Determination Processes*
  • Spermatogenesis / genetics


  • Drosophila Proteins
  • Ribonucleoproteins
  • tra2 protein, Drosophila